This application claims priority to UK Application Serial No. 9908016.0 (filed Apr. 8, 1999), Attorney Docket No. AF-57629. This application is hereby incorporated herein by reference in its entirety.
This invention relates to an electrical plug, and to a mechanism therefor, and in particular to a mechanism for an electrical plug in the form of an adaptor such as an AC adaptor having foldable pins.
In its simplest form an electrical plug such as a conventional electrical adaptor, for example an AC adaptor for use with various forms of electrical apparatus, may have a pair of adaptor pins 1 fixed so as to extend from the adaptor body 2. Such a conventional arrangement is shown in FIG. 1. While having the advantage of simplicity this arrangement has numerous disadvantages. The most important among these drawbacks are that since the pins are fixed, the adaptor takes up unnecessary space when not in use. In addition the pins represent sharp edges that again when not in use can be disadvantageous and even potentially dangerous. This is particularly true when the adaptor pins are in the form of blades that can be quite sharp.
Accordingly it is known to provide an adaptor in which the adaptor pins can be folded out of the way when the adaptor is not in use. An example of such a known adaptor is shown in FIG. 2. As in FIG. 1 the adaptor is provided with a pair of pins 1 and an adaptor body 2. In this adaptor however the pins 1 may be pivoted about their ends between a vertical position for use, and a horizontal position when not in use in which the pins 1 are received within slots 3 formed in the adaptor body 2. The pins 1 are pivotally mounted such that their ends distal from the pivots are located at an edge of the adaptor body 2, and this edge is provided with recessed portions 4 about the ends of the pins 1 such that the ends of the pins 1 can be engaged by a user""s fingers in order to move the pins from a horizontal non-operative position to a vertical operative position.
While the adaptor of FIG. 2 represents an improvement over the fixed pin adaptor of FIG. 1, it is not without its own disadvantages and drawbacks. Firstly, while when not in use most of the length of the pins 1 are received within the adaptor body 2 the ends of the pins 1 are still exposed (and indeed have to be to allow the pins 1 to be pivoted) and these exposed ends can still be dangerous. In addition the pivoting mechanism introduces its own drawbacks. To begin with, when assembling a conventional adaptor of the type shown in FIG. 2, screws or interlocking components must be used to hold the pins in place during assembly to prevent them being lost. Additionally providing the pivot point at the ends of the pins 1 located remote from the edge of the adaptor body 2 means that a relatively large space must be provided around the pivot mechanism to provide a large buffer safety clearance area. The recesses 4 reduce the amount of usable space within the adaptor body, and generally the design is complex and leads to a large adaptor body being needed.
According to the present invention there is provided an electrical plug comprising a body and at least two pins, said pins being movable between a first operative position in which the pins extend from the body, and a second non-operative position in which the pins are received within slots formed in the body, wherein said pins are pivotally mounted for movement between said first and second positions and wherein the pins pivot about a pivot axis located at an end of each respective pin adjacent an edge of said body whereby when said pins pivot from said second position to said first position, the ends of said pins distal from said pivot axis move towards said edge of said body, and wherein when the pins are said second position, said pins are completely received within the slots.
By means of this arrangement the pivot axis of the pins is located closer to the edge of the body than in the prior art and this allows a smaller clearance space to be used around the pins within the body. Furthermore because when the pins are in the nonoperative second position they are completely received within the slots, no sharp edges are exposed.
In a particularly preferred embodiment means are provided for releasing the pins from the second position prior to the pins being moved into the first position. Preferably this releasing means may comprise a tongue formed in a surface of the body and depression of which causes partial rotation of the pins such that the pins are caused to move to an intermediate position in which they project above the surface. This may be achieved by forming a projection on an underside of the tongue and engaging a member fixed to the pins so as to cause rotation thereof following depression of the tongue.
The member fixed to the pins may be a position locating member having three positions corresponding to the first, second and intermediate positions. Preferably, for example, the position locating member may be provided with three recesses corresponding to the three positions, and a locking pawl may be formed on the underside of the surface of the body for engagement with said recesses.
Preferably, in order to prevent the pins going beyond the first and second positions, means are provided for limiting movement of the pins. Such limiting means may comprise stop surfaces located within the body and which engage corresponding surfaces of a pivot body formed at an end of each pin.
In a particularly preferred embodiment of the invention the plug comprises two parallel pins and two corresponding parallel slots, each slot having an enlarged end for receiving an enlarged pivot body formed at one end of each pin, a position locating member being fixed to both the pivot bodies and located therebetween, and means for releasing the pins from said second position into an intermediate position prior to the pins being moved to the first position comprising a tongue formed in the adaptor body between the slots, the tongue being adapted to act upon said position locating member upon depression thereof.
Viewed from another broad aspect the present invention provides an electrical plug comprising a body and at least two pins, said pins being movable between a first operative position in which the pins extend from the body, and a second non-operative position in which the pins are received within slots formed in the body, wherein when the pins are in the second position they are completely received within the slots.
By means of this aspect of the present invention there is provided an electrical plug in which the pins may be folded away when not in use and with no part of the pins being exposed in a potentially dangerous manner.
Viewed from a still further aspect of the present invention there is provided an electrical plug comprising a body and at least two pins, the pins being movable between a first operative position in which the pins extend from the body, and a second nonoperative position in which the pins are received within slots formed in the body, wherein means are provided for releasing the pins from the second position to an intermediate position prior to moving the pins to the first position.
In this way a particuarly simple mechansim may be provided for releasing the pins from their slots so that a user does not have to use his or her fingers to extract the pins from the slots, with the risk of injury to the fingers if the pins are sharp.
The present invention is particularly suited for electrical plugs that serves as electrical adaptors, for example for laptop PCs, which must be carried around when not in use.
Viewed from another broad aspect the present invention provides a method for assembling an electrical plug of the type having at least two pins that are movable between a first operative position in which the pins extend from the plug body, and a second inoperative position in which the pins are received within slots formed in the plug body, comprising:
(a) inserting said pins through enlarged openings formed at the ends of said slots, said pins being inserted from the inner surface of a member forming the side of said plug being formed with said slots and said pins being inserted at an angle of approximately 45xc2x0 to said surface,
(b) rotating said pins so that they are fully received within said slots, and
(c) assembling said member to the remainder of said plug, wherein said inner surface of said member is formed with at least one surface for preventing disengagement of said pins from said member during the assembly operation.
The surface for preventing disengagement of the pins may, for example, be a surface that defines an underside of the slot, or a surface that acts upon pivot bodies formed at the end of the pins.